Light Emitting Diode and Manufacturing Method Thereof

ABSTRACT

A light emitting diode manufacturing method introduces a transparent enclosure to improve the uniformity of coating phosphor, so as to achieve the purposes of enhancing the uniform color temperature and the light emitting efficiency. The manufacturing method is used extensively for packaging various types of light emitting diode chips and mass production.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting diode and amanufacturing method thereof, and more particularly to a light emittingdiode manufacturing method and a light emitting diode manufactured bythe method capable of enhancing the uniformity of color temperature andthe light emitting efficiency of a white light emitting diode device.

2. Description of the Related Art

FIG. 1 illustrates a schematic view of a white light emitting diodedisclosed in U.S. Pat. No. 5,998,925. The white light emitting diode 1comprises a lead frame 11, a GaN-based light emitting diode chip 12 foremitting a light with a first wavelength, and a phosphor 13. Thephosphor 13 absorbs a part of radiation energy produced by the GaN-basedlight emitting diode chip 12 and emits a light with a second wavelength,so as to obtain a white light with a third wavelength mixed from firstand second wavelengths. In FIG. 1, the phosphor 13 and the first resinare mixed to form a mixed resin 14 containing the phosphor 13. Then themixed resin 14 is filled into a cup of the lead frame 11 that carriesthe GaN-based light emitting diode chip completely cover the GaN-basedlight emitting diode chip 12. A second resin 15 is then used for sealingthe lead frame 11, the GaN-based light emitting diode chip 12 and themixed resin 14 to complete the manufacture of the white light emittingdiode. Since the thickness of the mixed resin 14 filled in the cup ofthe lead frame can not controlled intentionally, the phosphor may bedistributed uniformly. Thus the brightness of the emitted lights indifferent directions and the color temperature are not uniform.

U.S. Pat. No. 5,959,316 discloses another a white light emitting diodedevice, which is illustrated in FIG. 2. A light emitting diode chip 22is placed on a lead frame 21, and then a first transparent packagingresin 23 is used to seal and cover the top of the light emitting diodechip 22. A mixed resin 24 is provided by a phosphor mixed with a secondtransparent packaging resin, and then the mixed resin 24 is used forsealing and covering the first transparent packaging resin 23. A thirdtransparent packaging resin 25 is used for sealing and covering themixed resin 24. Since the first transparent packaging resin 23 is bakedand dried to constitute a circular top, and therefore the mixed resin 24containing the phosphor can be coated onto the circular top with aspecific thickness to overcome the drawbacks of having the non-uniformangular distribution of color temperature of the light emitting device.The manufacturing method disclosed in the prior art involves producingthe first transparent packaging resin 23, mixed resin 24 and thirdtransparent packaging resin 25, and then performing an encapsulationprocess. The encapsulation process requires a step of baking and dryingfor each resin by a high temperature. Such manufacturing processes willcontaminate surfaces of the resins and cause an insufficient adhesiveforce between resins. Further it is difficult to improve the yield rateof the manufacturing process or simplify the manufacturing process.

FIG. 3 illustrates another light emitting element as disclosed in U.S.Pat. No. 6,576,488. This patent discloses a flip chip packaging methodand provides a selective electrophoresis deposition technology for aphosphor to improve the uniformity of the phosphor coated onto the lightemitting diode chip, so as to overcome the drawback of having anon-uniform angular distribution of color temperature. Firstly, thelight emitting diode chip 32 is mounted onto a substrate 31 by a flipchip manufacturing method. An electrophoresis apparatus 34 carrying aphosphor 33 is applied with a specific voltage such that the phosphor 33will be deposited on an exposed surface of the light emitting diode chip32. Since the phosphor 33 is distributed to have a uniform thickness,the uniformity of color temperature angular distribution can be improvedeffectively. Although the manufacturing process can improve theuniformity of color temperature angular distribution, the complexity ofthe chip manufacturing process and the manufacturing cost are likely toincrease since the process requires various photomasks for the lightemitting diode chip 32 and the substrate 31 to prevent phosphor frombeing deposited on a metal conductive area if the selectiveelectrophoresis deposition process is adopted.

FIG. 4 illustrates another method of producing a white light emittingdevice uniformly coated with a phosphor as disclosed in U.S. PatentPublication No. 20050244993. A light emitting diode chip 42 having avertical electrode structure is provided and mounted onto a substrate41, and then a phosphor mixed with another suspension is provided. Asthe mixed solution is sprayed at the periphery of the light emittingdiode chip 42, a phosphor coating layer 43 with a uniform thickness canbe formed to improve the uniformity of the color temperature angulardistribution effectively.

FIG. 5 illustrates another method of producing a white light emittingdevice uniformly coated with a phosphor as disclosed in U.S. Pat. No.7,217,583. A light emitting diode chip 52 is provided and mounted onto asubstrate 51, and then a phosphor mixed with a mixed solution 53 of asuspension is provided and formed on the light emitting diode chip 52.Then, the mixed solution 53 is confined and the evaporation process ofthe mixed solution 53 is controlled to form a phosphor coating layer 54with a uniform thickness at the periphery of the light emitting diodechip 52 to improve the uniformity of the color temperature angulardistribution effectively.

Thus, there is a need to develop a new method to uniformly coat aphosphor at the periphery of a light emitting diode chip and a lightemitting diode manufactured by this method to simplify the manufactureprocess and the cost.

SUMMARY OF THE INVENTION

In view of the shortcomings of the prior art, a light emitting diode anda manufacturing method thereof are provided to overcome the problem ofhaving a non-uniform color temperature angular distribution caused by anon-uniform phosphor.

The light emitting diode manufacturing method, particularly a method ofpackaging a light emitting diode chip by a transparent enclosure, mayovercome the problem of having a non-uniform color temperature angulardistribution caused by a non-uniformly coated phosphor and improve thelight emitting efficiency of light emitting diode device.

The light emitting diode manufacturing method, particularly a method ofpackaging a light emitting diode chip by a transparent enclosure mayfurther achieve the effects of simplifying the manufacturing process andreducing the cost.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, theembodiment of this disclosure discloses a light emitting diodemanufacturing method comprising the steps of: providing a lead frame;mounting at least one light emitting diode chip onto the lead frame;electrically coupling the light emitting diode chip and the lead frame;forming a transparent enclosure to enclose the light emitting diodechip; and coating a packaging resin containing a phosphor in an areahaving the light emitting diode chip and enclosed by the enclosure.

The embodiment of this disclosure discloses a white light emittingdiode, comprising a lead frame, a light emitting diode chip, atransparent enclosure and a mixed resin having a phosphor. The lightemitting diode chip is mounted onto the lead frame. The transparentenclosure is provided for enclosing the light emitting diode chip. Themixed resin containing a phosphor is formed in an area enclosed by theenclosure.

In summation of the description above, the light emitting diode and itsmanufacturing method in accordance with the present invention have oneor more of the following technical effects. The light emitting diode andthe manufacturing method thereof enclose the light emitting diode chipby the transparent enclosure to improve the uniformity of coating thephosphor and the light emitting efficiency of the light emitting diodedevice. The light emitting diode and the manufacturing method thereofenclose the light emitting diode chip by the transparent enclosure toachieve the effects of simplifying the process of uniformly coating thephosphor and reducing the manufacturing cost.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a schematic view of a first conventional white light emittingdiode;

FIG. 2 is a schematic view of a second conventional white light emittingdiode;

FIG. 3 is a schematic view of a third conventional white light emittingdiode;

FIG. 4 is a schematic view of a fourth conventional white light emittingdiode;

FIG. 5 is a schematic view of a fifth conventional white light emittingdiode;

FIG. 6 is a schematic view of a light emitting diode in accordance withthe present invention;

FIGS. 7A-7C are schematic views showing the manufacturing procedure of alight emitting diode in accordance with the present invention; and

FIG. 8 is a schematic view of another light emitting diode in accordancewith the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments,examples of which are illustrated in the accompanying drawings.

With reference to FIG. 6 for a schematic view of a light emitting diodein accordance with the present invention, the manufacturing process ofthe light emitting diode comprises the steps of: providing a lead frame61, mounting a light emitting diode chip 62 onto the lead frame 61,forming an enclosure 63 for enclosing the light emitting diode chip 62and providing at least one mixed resin 64 containing a phosphor in theenclosure 63 to cover onto the light emitting diode chip 62. Theenclosure 63 can be formed by a spray coating method, a screen coatingmethod, a sol-gel method, a dispensing method, a die-casting method orthe like. The lead frame 61 can be made of a composite material selectedfrom the group of a ceramic based material, an aluminum oxide based(AlO-based) material, copper, aluminum, molybdenum, tungsten, and analuminum nitride based (AlN-based) material. The lead frame 61 furtherincludes a bonding area 65, an electrically connected circuit 68, a pad69, and an electrode terminal 70. In addition, the bonding area 65 canbe made of a conductor, a non-conductor, or their mixture. The lightemitting diode chip 62 and the enclosure 63 have a relative distancewith each other. A preferred distance can be adjusted according to thesize of the light emitting diode chip 62 and the lead frame 61. Theenclosure 63 is made of a transparent material, and the predeterminedthickness of the mixed resin 64 disposed on the light emitting diodechip 62 can be adjusted according to the size of the light emittingdiode chip 62 and the lead frame 61. The predetermined thickness of themixed resin 64 is not smaller than the relative distance between an edgeof the light emitting diode chip 62 and the enclosure 63. A methodselected from the collection of a sputtering method, a chemical vapordeposition method, a spray coating method, a screen coating method, avacuum evaporation method, sol-gel method, and a dispensing method, orany combination of the above is used for forming the mixed resin 64 inan area enclosed by the enclosure. The phosphor in the mixed resin 64can be Sr_(1-x-y)Ba_(x)Ca_(y)SiO₄:Eu²⁺F,(Sr_(1-x-y)Eu_(x)Mn_(y))P_(2+z)O₇:Eu²⁺F, (Ba,Sr,Ca)Al₂O₄:Eu,((Ba,Sr,Ca)(Mg,Zn))Si₂O₇:Eu, SrGa₂S₄:Eu,((Ba,Sr,Ca)_(1-x)Eu_(x))(Mg,Zn)_(1-x)Mn_(x)))Al₁₀O₁₇,Ca₈Mg(SiO₄)₄Cl₂:Eu,Mn, ((Ba,Sr,Ca,Mg)_(1-x)Eu_(x))₂SiO₄, Ca₂MgSi₂O₇:Cl,SrSi₃O₈.2SrCl₂:Eu, BAM:Eu, Sr-Aluminate:Eu, Thiogallate:Eu,Chlorosilicate:Eu, Borate:Ce,Tb, Sr₄Al₁₄O₂₅:Eu, YBO₃:Ce,Tb,BaMgAl₁₀O₁₇:Eu,Mn, (Sr,Ca,Ba)(Al,Ga)₂S₄:Eu, Ca₂MgSi₂O₇:Cl,Eu,Mn,(Sr,Ca,Ba,Mg)₁₀(PO₄)₆Cl₂:Eu ZnS:Cu,Al,(Y,Gd,Tb,Lu,Yb)(Al_(y)Ga_(1-y))₅O₁₂:Ce,(Sr_(1-x-y-z)Ba_(x)Ca_(y)Eu_(z))₂SiO₄,(Sr_(1-a-b)Ca_(b)Ba_(c))Si_(x)N_(y)O_(z):Eu_(a) and Sr₅(PO₄)₃Cl:Eu_(a)or a mixture of any combination of the above. The enclosure 63 is madeof a transparent material, wherein the transparent material can be atransparent resin such as transparent epoxy resin or silicon resin, orcan be a material selected from the collection of silicon dioxide,glass, and an encapsulating material. To achieve the effects of thepresent invention, the invention provides a manufacturing processdescribed as follows. With reference to FIG. 7A, the light emittingdiode chip 62 is mounted onto the bonding area 65 of the lead frame 61,and then a metal lead 71 is used for connecting an anode 66 and acathode 67 of the light emitting diode chip 62 onto a pad 69 of the leadframe. With reference to FIG. 7B, after the step of connecting the metallead 71, a transparent enclosure 63 is provided to enclose the lightemitting diode chip 62 to define a space 100. The enclosure 63 can beformed by a spray coating method, a screen coating method, a sol-gelmethod, a dispensing method or a die-casting method. A mixed resin 64containing a phosphor is filled up in the space 100 to complete themanufacture of the white light emitting diode concurrently featuring auniform color temperature and a uniform angular distribution ofbrightness. With reference to FIG. 7C, a step of planarizing a surfaceof the mixed resin 64 can be added to the procedure. In the foregoingprocedure as disclosed in FIG. 7B, the transparent enclosure 63 isdisposed on the lead frame 61, and then the light emitting diode chip 62is mounted onto the bonding area 65 of the lead frame 61. Thetransparent enclosure 63 of this preferred embodiment is made of atransparent material, and the transparent material can be a transparentresin such as transparent epoxy resin or silicon resin, or can be madeof a material such as silicon dioxide, glass, and an encapsulationmaterial.

With reference to FIG. 8 for a schematic view of a structure of anotherlight emitting diode in accordance with the present invention, theconductive wire circuit is omitted in the figure. The manufacturingprocess of the light emitting diode is described as follows. A leadframe 81 is provided, and a plurality of light emitting diode chips 82are mounted onto the lead frame 81 to form a plurality of transparentenclosures 83, each for enclosing the light emitting diode chip 82 todefine a plurality of spaces. The enclosures 83 can be formed by a spraycoating method, a screen coating method, a sol-gel method, a dispensingmethod or a die-casting method, and then a mixed resin 84 containing aphosphor is filled up in the plurality of spaces to complete themanufacture of white light emitting diode concurrently featuring auniform color temperature and a uniform angular distribution ofbrightness. A step of planarizing a surface of the mixed resin 84 can beadded to the procedure. In this embodiment, the transparent enclosure 83is made of a transparent material, and the transparent material can be atransparent resin such as transparent epoxy resin or silicon resin, orcan be made of a material such as silicon dioxide, glass, or anencapsulation material.

In summation of the description above, the present invention uses thetransparent enclosure to enclose the light emitting diode chip toimprove the uniformity of the coated phosphor and the light emittingefficiency of the light emitting diode device, and the invention furthersimplifies the procedure of uniformly coating the phosphor and reducesthe manufacturing cost.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A light emitting diode manufacturing method, comprising the steps of:providing a lead frame; mounting at least one light emitting diode chiponto the lead frame; forming at least one transparent enclosure toenclose the light emitting diode chip; and disposing a mixed resincomprising at least one phosphor in an area enclosed by the transparentenclosure.
 2. The light emitting diode manufacturing method of claim 1,wherein a distance is maintained between the transparent enclosure andan edge of the light emitting diode chip.
 3. The light emitting diodemanufacturing method of claim 2, wherein the mixed resin comprising thephosphor has a predetermined thickness.
 4. The light emitting diodemanufacturing method of claim 3, wherein the distance from thetransparent enclosure to the edge of the light emitting diode chip isnot greater than the predetermined thickness of the mixed resincomprising the phosphor.
 5. The light emitting diode manufacturingmethod of claims 1, further comprising a step of electrically couplingthe light emitting diode chip to the lead frame.
 6. The light emittingdiode manufacturing method of claim 5, wherein after the step ofmounting at least one light emitting diode chip onto the lead frame,further comprising the step of: electrically coupling the light emittingdiode chip to the lead frame.
 7. The light emitting diode manufacturingmethod of claim 5, wherein after the step of forming at least onetransparent enclosure to enclose the light emitting diode chip, furthercomprising the step of: electrically coupling the light emitting diodechip to the lead frame.
 8. The light emitting diode manufacturing methodof claim 1, further comprising a step of planarizing a surface of themixed resin.
 9. The light emitting diode manufacturing method of claim8, wherein a distance from a surface of the light emitting diode chip toa surface of the mixed resin is greater than or equal to a distance froma side wall of the light emitting diode chip to an inner surface of thetransparent enclosure.
 10. The light emitting diode manufacturing methodof claim 1, further comprising a step of connecting an anode and acathode of the light emitting diode chip to the lead frame.
 11. Thelight emitting diode manufacturing method of claim 10, furthercomprising a step of the connecting the anode and the cathode of thelight emitting diode chip to a thermal conduction pad of the lead frame.12. The light emitting diode manufacturing method of claims 1, whereinthe phosphor is made of a material selected from the group consisting ofSr_(1-x-y)Ba_(x)Ca_(y)SiO₄:Eu²⁺F,(Sr_(1-x-y)Eu_(x)Mn_(y))P_(2+z)O₇:Eu²⁺F, (Ba,Sr,Ca)Al₂O₄:Eu,((Ba,Sr,Ca)(Mg,Zn))Si₂O₇:Eu, SrGa₂S₄:Eu,((Ba,Sr,Ca)_(1-x)Eu_(x))(Mg,Zn)_(1-x)Mn_(x)))Al₁₀O₁₇,Ca₈Mg(SiO₄)Cl₂:Eu,Mn, ((Ba,Sr,Ca,Mg)_(1-x)Eu_(x))₂SiO₄, Ca₂MgSi₂O₇:Cl,SrSi₃O₈.2SrCl₂:Eu, BAM:Eu, Sr-Aluminate:Eu, Thiogallate:Eu,Chlorosilicate:Eu, Borate:Ce,Tb, Sr₄Al₁₄O₂₅:Eu, YBO₃:Ce,Tb,BaMgAl₁₀O₁₇:Eu,Mn, (Sr,Ca,Ba)(Al,Ga)₂S₄:Eu, Ca₂MgSi₂O₇:Cl,Eu,Mn,(Sr,Ca,Ba,Mg)₁₀(PO₄)₆C₁₂:Eu ZnS:Cu,Al,(Y,Gd,Tb,Lu,Yb)(Al_(y)Ga_(1-y))₅O₁₂:Ce,(Sr_(1-x-y-z)Ba_(x)Ca_(y)Eu_(z))₂SiO₄,(Sr_(1-a-b)Ca_(b)B_(ac))Si_(x)N_(y)O_(z):Eu_(a) and Sr₅(PO₄)₃Cl:Eu_(a)or a mixed material of any combination of the above.
 13. The lightemitting diode manufacturing method of claims 1, wherein the step offorming the resin containing a phosphor in the area enclosed by theenclosure is performed by a method selected from the group consisting ofa sputtering method, a chemical vapor deposition method, a spray coatingmethod, a screen coating method, a vacuum evaporation method, a sol-gelmethod and a dispensing method or any combination of the above.
 14. Alight emitting diode, comprising: a lead frame; a light emitting diodechip mounted onto the lead frame; a transparent enclosure enclosing thelight emitting diode chip; and a mixed resin containing at least onephosphor and being formed in an area enclosed by the transparentenclosure.
 15. The light emitting diode of claim 14, wherein thetransparent enclosure and an edge of the light emitting diode chip havea distance.
 16. The light emitting diode of claim 15, wherein the mixedresin containing the phosphor has a predetermined thickness.
 17. Thelight emitting diode of claim 16, wherein the distance between thetransparent enclosure and the edge of the light emitting diode chip isnot greater than the predetermined thickness of the mixed resincontaining the phosphor.
 18. The light emitting diode of claims 14,wherein the lead frame further comprises an electrically connectedcircuit coupled to the light emitting diode chip and the lead frame. 19.The light emitting diode of claims 14, wherein the mixed resin has aplanarized surface.
 20. The light emitting diode of claim 14, wherein adistance from a surface of the light emitting diode chip to a surface ofthe mixed resin is greater than or equal to a distance from a side wallof the light emitting diode chip to an inner surface of the enclosure.21. The light emitting diode of claims 14, wherein the lead frame has abonding area provided for mounting the light emitting diode chip. 22.The light emitting diode of claim 14, further comprising a metal leadprovided for connecting the light emitting diode chip onto the leadframe.
 23. The light emitting diode of claim 22, wherein the lead framefurther comprises a thermal conduction pad, and the metal lead isprovided for connecting an anode and a cathode of the light emittingdiode chip to the thermal conduction pad.
 24. The light emitting diodeof claims 14, wherein the phosphor is made of a material selected fromthe group consisting of Sr_(1-x-y)Ba_(x)Ca_(y)SiO₄:Eu²⁺F,(Sr_(1-x-y)Eu_(x)Mn_(y))P_(2+z)O₇:Eu²⁺F, (Ba,Sr,Ca)Al₂O₄:Eu,((Ba,Sr,Ca)(Mg,Zn))Si₂O₇:Eu, SrGa₂S₄:Eu,((Ba,Sr,Ca)_(1-x)Eu_(x))(Mg,Zn)_(1-x)Mn_(x)))Al₁₀O₁₇,Ca₈Mg(SiO₄)₄Cl₂:Eu,Mn, ((Ba,Sr,Ca,Mg)_(1-x)Eu_(x))₂SiO₄, Ca₂MgSi₂O₇:Cl,SrSi₃O₈.2SrCl₂:Eu, BAM:Eu, Sr-Aluminate:Eu, Thiogallate:Eu,Chlorosilicate:Eu, Borate:Ce,Tb, Sr₄Al₁₄O₂₅:Eu, YBO₃:Ce,Tb,BaMgAl₁₀O₁₇:Eu,Mn, (Sr,Ca,Ba)(Al,Ga)₂S₄:Eu, Ca₂MgSi₂O₇:Cl,Eu,Mn,(Sr,Ca,Ba,Mg)₁₀(PO4)₆Cl₂:Eu ZnS:Cu,Al,(Y,Gd,Tb,Lu,Yb)(Al_(y)Ga_(1-y))₅O₁₂:Ce,(Sr_(1-x-y-z)Ba_(x)Ca_(y)Eu_(z))₂SiO₄,(Sr_(1-a-b)Ca_(b)Ba_(c))Si_(x)N_(y)O_(z):Eu_(a) and Sr₅(PO₄)₃Cl:Eu_(a)or a mixture of any combination of the above.
 25. The light emittingdiode of claims 14, wherein the mixed resin is formed in the areaenclosed by the enclosure by a method selected from the group consistingof a sputtering method, a chemical vapor deposition method, a spraycoating method, a screen coating method, a vacuum evaporation method, asol-gel method and a dispensing method.